Because it is. Your voice is a finite resource when you’re a voice actor. They’re basically independent contractors and you keep comparing them to salaried employees.
Broadway is also kind of a bad example since people tend to do that more for their resume, personal desire and the prestige involved than the paycheck.
Again, if people think it’s too much, they can pay their friend or neighbor to do it and get the results you’d expect.
They do. That’s why you’re paying $800 an hour. It’s what their time is worth and what the market has determined people will pay for it.